The present invention relates to fill detection devices for grass containers of lawn mowers and to grass containers provided with such a device.
When the cut grass that has accumulated in the grass container has reached a preset amount, e.g. when the grass container is fill, then such a fill detection device can detect that the amount of cut grass retained in the grass container has reached the preset amount through a detection operation of a detection means in which a pivot sensor is pivoted downward by the pressure exerted by the cut grass.
As this type of detection sensor, a sensor is known that is provided with a lever 88 (corresponding to a pivot sensor) that is supported by a mounting member 92 pivotably around a rotation axis 108, and an electric switch 96 in which a switch button 100 is actuated via a plate spring 98 by a second portion 102 of the lever 88, as shown in U.S. Pat. No. 6,272,818 (see cols. 7, 8, 9 and FIGS. 4 to 7).
Furthermore, as shown in this document, through the rotation of a swing arm 106 that is operatively fixed to the mounting member 92 around an axis 126, the mounting member 92 rotates together with the swing arm 106 around the axis 126, putting the lever 88 into a posture in which it extends in a relatively straight horizontal direction or into a vertical posture.
That is to say, by changing the angular position of the lever 88, it is possible to adjust the orientation of the pressure-sensing surface of the lever 88 such that the pressure-sensing surface when the lever 88 is in a raised non-detection posture is on the side facing upward or on the side facing sideways.
In this type of fill detection device, the pivot sensor is arranged nearly below the cut grass inlet port of the grass container, such that a detection is made before the cut grass collected in the grass container accumulates near the cut grass inlet port of the grass container and causes jamming of the cut grass inlet port.
As for the cut grass, there is light cut grass that is dry, and there is cut grass that is heavy e.g. because it is wet. In the case of light cut grass, the cut grass that is fed into the grass container falls down while being spread as it comes flying into the grass container, and tends to accumulate at a substantially uniform accumulation height over the entire area of the container. Also, if the pivot sensor receives the pressure exerted by the cut grass from a lateral direction when viewed from the direction of the pivot axis of the pivot sensor, then the efficiency with which the cut grass acts on the pivot sensor in order to pivot the pivot sensor is relatively poor. Therefore, in the case of light cut grass, if the pivot sensor is adapted to receive the pressure exerted by the cut grass from a lateral direction, then already much more cut grass than the preset amount may have accumulated when the pivot sensor pivots downward and the detection means is actuated, and cut grass may easily accumulate up to the cut grass inlet port.
In the case of heavy cut grass, the cut grass that is fed into the container falls down without being spread within the grass container, and tends to accumulate with an accumulation height that is higher at locations further removed from the cut grass inlet port than at locations close to the cut grass inlet port. Moreover, if the pivot sensor is adapted to receive the pressure exerted by the cut grass from a vertical direction with respect to the grass container, then the pivot sensor does not easily pivot downward as long as there is not very much cut grass above the pivot sensor, even when a relatively large amount of cut grass has accumulated in the grass container. Therefore, in the case of heavy cut grass, if the pivot sensor is adapted to receive the pressure exerted by the cut grass from above, then already much more cut grass than the preset amount may have accumulated when the pivot sensor pivots downward and the detection means is actuated, and cut grass may easily accumulate up to the cut grass inlet port.
When employing the above-described conventional detection technology, in the case of light cut grass, it is possible to realize a detection state in which the pivot sensor receives the pressure exerted by the cut grass from above by adjusting the angle of the pivot sensor such that the pressure-sensing surface of the pivot sensor faces upward, and in the case of heavy cut grass, it is possible to realize a detection state in which the pivot sensor receives the pressure exerted by the cut grass from the side by adjusting the angle of the pivot sensor such that the pressure-sensing surface of the pivot sensor faces to the side, but this requires the bothersome task of performing an angular adjustment of the pivot sensor depending on the weight or moisture of the cut grass.